A Compact Millimeter-Wave Quad-Core Class-F 23 VCO Using Inter-Core-Shaping Technique

A compact millimeter-wave (mm-wave) quad-core Class-F23voltage-controlled oscillator (VCO) using an inter-core-shaping is proposed in this letter. Based on the complementary currents between pMOS and nMOS cores, both common mode (CM) and differential mode (DM) tanks are established with low complexity. An eight-port triple-coil Class-F transformer is designed to achieve second and third harmonic impedance peaks in the CM and DM operations, respectively, resulting in the phase noise (PN) reduction. Fabricated in a 65-nm CMOS, the VCO has a tuning range of 16.8% from 25.6 to 30.3 GHz. The measured peak PN at 1-MHz offset is −111 dBc/Hz, with a small core area of 0.096 mm2. It demonstrated that the proposed topology can solve the conflict between the complicated design of harmonic control and compact size in the mm-wave, thereby enhancing the PN performance and compactness simultaneously.